A study has been initiated to define the possible etiologic role of herpesvirus in human prostatic neoplasia. Benign and malignant prostatic and urinary bladder specimens are being cultivated in vitro. Transformation of human cell cultures with SV40 has provided stable lines of prostatic carcinoma. Efforts to transform other prostate-derived cell lines with inactivated herpesvirus (HSV2) as well as with SV40 are under way. Fresh sections and cell cultures are being examined by immunofluorescence for the presence of infectious HSV as well as for subviral precursors. Methods to promote viral rescue including cocultivation techniques and chemical induction are currently in routine use. Attempts at detection of herpesvirus DNA sequences employing molecular hybridization will be tried when sufficient materials are available.